The invention relates to improvements in methods of and in apparatus for ascertaining the hardness of elastically deformable rod-shaped articles of the tobacco processing industry. More particularly, the invention relates to improvements in methods of and in apparatus for mechanically testing plain or filter cigarettes, cigars, cigarillos, cheroots and/or other rod-shaped articles of the tobacco processing industry for the purpose of ascertaining their hardness.
Commonly owned U.S. Pat. No. 4,974,443, granted Dec. 4, 1990 to Uwe Heitmann for "Method of and apparatus for ascertaining the hardness of cigarettes and the like" discloses the utilization of one or more pivotable levers which act not unlike weights and subject successive cigarettes of a series of such rod-shaped articles to a radially oriented deforming action. The extent of mechanically induced deformation is measured, and the results of such measurement are utilized to regulate the operation of the cigarette rod making or filter tipping machine in order to ensure that the hardness of cigarettes will match an optimum value. The articles to be tested are moved sideways, i.e., substantially at right angles to their longitudinal axes, and each lever can simultaneously deform two or more cigarettes of such series.
As used herein, the term "hardness" is intended to denote the resistance of rod-shaped articles of the tobacco processing industry (hereinafter referred to as cigarettes or filter cigarettes but intended to embrace all kinds of rod-shaped articles of the tobacco processing industry which contain filter material for tobacco smoke and/or natural, reconstituted and/or substitute tobacco) to elastic deformation of their fillers in response to the application of mechanical stresses to the external surfaces of their wrappers. For example, such mechanical stress will be applied by the fingers of a person who is about to light or who is in the process of smoking a cigarette. The hardness of cigarettes is a function of the so-called filling power of shreds or filaments of tobacco or filter material. The filling power is the ability of a predetermined quantity of tobacco or filter material to fill the tubular wrapper of a rod-shaped article of the tobacco processing industry. Thus, the filling power is clearly related to the hardness of cigarettes.
A plain or filter cigarette is likely to be subjected to a number of mechanical and/or other deforming stresses before it reaches the hardness testing station. For example, a filter cigarette is likely to be mechanically deformed (so that its cross-sectional outline is not an ideal circular outline) during subdivision of a continuous cigarette rod into plain cigarettes of unit length or multiple unit length, during the application of uniting bands of tipping paper which are used to connect plain cigarettes with filter plugs (such application involves rolling the uniting bands around coaxial plain cigarettes and filter plugs), during severing of filter plugs to divide filter cigarettes of double unit length into filter cigarettes of unit length, as well as during repeated transfer of cigarettes and their components from conveyor to conveyor which often involves attracting the cigarettes by suction and/or pressing the cigarettes against the peripheries of rotary conveyors by shrouds and/or other mechanical means. Each such treatment is likely to affect the cross-sectional outline of the cigarettes ahead of the mechanical hardness testing station. A frequent deformation is that which imparts to the cigarettes an oval shape and is likely to greatly affect the accuracy of mechanical hardness measurements which are based on the presumption that a cigarette to be tested has an ideal circular cross-sectional outline. An oval cigarette is held on its conveyor or conveyors in a predetermined orientation which does not change ahead of or at the hardness testing station because, as a rule, the cigarettes are attracted to their conveyors by suction. In other words, an oval cigarette is not likely to change its cross-sectional outline on the way toward the mechanical hardness testing station because it is not permitted to roll, i.e., to perform a movement which would be likely to at least partially restore its desirable circular cross-sectional outline. As a rule, testing of hardness is carried out while the cigarettes are confined in axially parallel peripheral flutes of a rotary drum-shaped conveyor having suction ports which communicate with the flutes and attract the cigarettes to the rotary conveyor, An oval cigarette which has entered a flute of such conveyor will remain oval during advancement past the mechanical hardness testing instrumentality or instrumentalities.